By Fineline Cube Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (HKG: 6990) unveiled first-in-human clinical data for its investigational B7-H3-targeting antibody-drug conjugate (ADC) SKB500 at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, demonstrating robust antitumor activity across six distinct solid tumor types with a favorable safety profile at the 12 mg/kg dose level.
The novel ADC achieved an objective response rate (ORR) of 42.7% and disease control rate (DCR) of 83.9% among 124 patients with advanced solid tumors, positioning SKB500 as a promising addition to the competitive B7-H3 therapeutic landscape.
Clinical Trial Overview & Patient Population
| Parameter | Detail |
|---|---|
| Study Type | First-in-human Phase I |
| Presentation Venue | ASCO Annual Meeting 2026 |
| Total Patients (12 mg/kg cohort) | 124 patients |
| Minimum Follow-up | 6 weeks |
| Tumor Types Evaluated | Small cell lung cancer (SCLC), esophageal squamous cell carcinoma (ESCC), head and neck squamous cell carcinoma (HNSCC), pancreatic ductal adenocarcinoma (PDAC), non-small cell lung cancer (NSCLC), nasopharyngeal carcinoma (NPC) |
| Optimal Dose Identified | 12 mg/kg (superior safety vs. 16 mg/kg) |
ADC Engineering Features
- Antibody Properties: High affinity, high hydrophilicity, enhanced endocytosis capability
- Fc Engineering: Silenced Fc effector function in constant region to reduce off-target toxicity
- Payload: Moderately toxic cytotoxic agent optimized for therapeutic index
- Linker Technology: Cleavable hydrophilic linker for controlled payload release
- Drug-to-Antibody Ratio (DAR): Approximately 8 (high DAR for enhanced potency)
- Target: B7-H3 (tumor-associated antigen overexpressed across multiple solid tumors)
Efficacy Results – 12 mg/kg Cohort (n=124)
| Endpoint | Result |
|---|---|
| Objective Response Rate (ORR) | 42.7% |
| Disease Control Rate (DCR) | 83.9% |
| Tumor Types with Activity | SCLC, ESCC, HNSCC, PDAC, NSCLC, NPC |
| Response Breadth | Activity observed across histologically diverse tumor types |
| Clinical Significance | Robust responses in traditionally difficult-to-treat cancers including pancreatic and SCLC |
Safety Profile & Dose Optimization
- Recommended Dose: 12 mg/kg selected based on superior safety profile
- Dose Comparison: 12 mg/kg demonstrated more favorable tolerability than 16 mg/kg cohort
- Therapeutic Index: High efficacy coupled with manageable safety supports continued development
- ADC-Specific Toxicities: No significant off-target effects reported due to Fc silencing design
Strategic Implications for Kelun-Biotech
- ADC Platform Validation: Success validates Kelun-Biotech’s proprietary ADC engineering capabilities
- B7-H3 Competitive Position: Enters crowded but promising B7-H3 field with differentiated high-DAR approach
- Global Development Potential: Strong ASCO presentation facilitates international partnership opportunities
- Pipeline Diversification: Expands beyond traditional small molecules into advanced biotherapeutics
- Market Opportunity: Addresses significant unmet needs in multiple solid tumor indications with limited treatment options
Competitive Landscape Analysis
- B7-H3 Field: Growing interest from major pharma companies with multiple ADCs in development
- Differentiation Factors: High DAR (8), hydrophilic linker, Fc-silenced antibody, broad tumor activity
- Clinical Benchmark: 42.7% ORR compares favorably to other early-stage B7-H3 ADCs
- Development Stage: First-in-human data positions Kelun-Biotech competitively in race to market
Market Impact Considerations
- Treatment Paradigm: Potential new option for patients with B7-H3-positive solid tumors failing standard therapies
- Commercial Strategy: Likely focus on tumor types with highest unmet need (pancreatic, SCLC, HNSCC)
- Pricing Premium: Advanced ADC technology supports premium pricing in oncology market
- Global Ambitions: Data supports potential regulatory filings beyond China in major markets
Forward-Looking Statements
This brief contains forward-looking statements regarding clinical development, regulatory pathways, and commercial potential for SKB500. Actual results may differ due to clinical trial outcomes, competitive dynamics, and regulatory decisions.-Fineline Info & Tech